Here, 5 students are to be selected from n students. When 2 specified students are included, then remaining 3 students can be selected (n−2) students ∴ Number of ways of selecting 3 student from n students =(n−2)C3 Now, when 2 specified students are not included, then 5 students can be selected from the remaining (n−2) students. ∴ Number of ways of selecting 5 students from (n−2) students =n−2C5 According to question, n−2C3:n−2C5=2:3 ⇒